Secondary battery aluminum-plastic film and soft-pack battery coated with the aluminum-plastic film

Abstract

The present invention provides an aluminum-plastic film for a secondary battery and a soft-pack battery coated with the aluminum-plastic film, and relates to the technical field of secondary batteries. The film layer is provided with an edge sealing portion and a liquid injection portion on the outside of the film layer, and a reserved hole is opened on the surface of the film layer and on a side away from the liquid injection portion. A folding line is provided on the surface of the film layer near the reserved hole, and the film layer is folded along the folding line to shield the reserved hole; the film layer is a composite material of a nylon layer, an aluminum foil layer and a heat-sealing layer; the film layer is folded and edge sealed along the center line to form a bag shape; the reserved hole is communicated with the inside of the film layer bag; the folding line is located at the edge corner of the film layer, and the film layer is triangularly folded along the folding line; the triangular folding position of the film layer is fixed to the surface of the film layer by bonding or stamping or a combination of the two, and the reserved hole is sealed at the triangular folding position of the film layer, so as to suppress the speed and intensity of pressure release, improve battery safety, slow down the temperature diffusion and fire speed of the battery pack, and further improve the safety of the battery.

Description

Technical Field

[0001] The present invention relates to the field of secondary batteries, in particular to an aluminum-plastic film for a secondary battery and a soft-pack battery coated with the aluminum-plastic film. Background Art

[0002] Soft-pack lithium-ion batteries offer advantages such as high energy density, excellent safety, and a compact size, making them widely used in 3C digital electronics, handheld power tools, energy storage devices, and new energy vehicles. Currently, soft-pack lithium-ion batteries are packaged using aluminum-plastic composite film. A punching die forms a concave packaging groove in the film, and the battery cell stack is placed within the groove and heat-sealed around its perimeter to encapsulate the battery. Therefore, the structure and process of punching, encapsulating, and folding the aluminum-plastic composite film significantly impact the energy density, reliability, workability, service life, and safety of soft-pack lithium-ion batteries.

[0003] At present, the conventional punching and packaging methods for soft-pack lithium-ion batteries are all equal-depth punching and packaging, which mainly have two types: the first is equal-depth punching and three-sided packaging, in which a piece of aluminum-plastic composite film is stamped to obtain two packaging grooves of equal depth, the battery stack is placed in one of the packaging grooves, and the other packaging groove is folded onto the packaging groove, the positive and negative tabs and the non-folded sides are finely sealed, while the folded sides are not finely sealed. The second is equal-depth punching and four-sided packaging, in which two pieces of aluminum-plastic composite film are stamped to obtain equal-depth packaging grooves located on the two pieces of aluminum-plastic composite film, the battery stack is placed in one of the packaging grooves, and the other packaging groove is placed on the packaging groove, and the positive and negative tabs and the two sides are finely sealed.

[0004] At present, after vacuum packaging, soft-pack batteries are damaged, the internal air pressure is too high and they are prone to explosion. Traditional soft-pack batteries have no pressure relief channels. When the battery explodes, the pressure is released to the four sides of the aluminum-plastic film, which is more dangerous. In addition, soft-pack batteries are often stacked. If one battery explodes, the large-scale pressure release can easily affect other batteries, causing fires and explosions between battery packs, posing a safety hazard. Summary of the Invention

[0005] The present invention aims to provide an aluminum-plastic film for a secondary battery and a soft-pack battery coated with the aluminum-plastic film to solve the above-mentioned technical problems. To achieve this purpose, the present invention adopts the following technical solutions:

[0006] Secondary battery aluminum plastic film, including

[0007] The membrane layer is provided with an edge sealing portion and a liquid injection portion on the outside of the membrane layer, and a reserved hole is opened on the side of the membrane layer surface away from the liquid injection portion, and a folding line is provided on the surface of the membrane layer near the reserved hole, and the membrane layer is folded along the folding line to cover the reserved hole;

[0008] This design reserves holes as pressure relief channels, which can reduce the impact when the battery cell bulges and explodes.

[0009] A further preferred solution: the film layer is a composite material of a nylon layer, an aluminum foil layer and a heat-sealing layer;

[0010] This design has high film toughness and can well encapsulate the bare roll core.

[0011] A further preferred solution is that the film layer is folded along the center line and sealed to form a bag shape.

[0012] Furthermore, the reserved hole is communicated with the inside of the film bag;

[0013] This design uses a bag-like film layer to encapsulate the bare roll core and reserve holes for pressure relief.

[0014] A further preferred solution is that the folding line is located at the corner of the film layer, and the film layer is folded in a triangular shape along the folding line;

[0015] Furthermore: the triangular folding position of the film layer is fixed to the surface of the film layer by bonding or stamping or a combination of both, and the reserved hole is sealed at the triangular folding position of the film layer;

[0016] In this design, the triangular folding position can play a buffering role during the pressure relief process.

[0017] A further preferred solution is that the triangular folded portion of the film layer is bonded with adhesive.

[0018] With this design, the rubber patch can further play a buffering role during the pressure relief process.

[0019] A further preferred embodiment is as follows: a bare core is contained in the bag structure of the film layer, and a tab is provided on one side of the bare core, the tab corresponding to the liquid injection portion of the film layer, the electrolyte is injected into the bag structure through the liquid injection portion, and the liquid injection portion is sealed and closed to form a soft pack battery;

[0020] Further: the outer end of the tab extends out of the film layer;

[0021] Connect electricity through the tabs.

[0022] Beneficial effects of the present invention:

[0023] 1. In order to improve the sealing performance of the reserved holes and avoid leakage in the later stage, glue is applied to the outside of the triangular folding position of the membrane layer. The glue protects the folding position of the membrane layer to avoid damage caused by wear and tear.

[0024] 2. When the battery swells or explodes due to impact or damage, the internal pressure of the battery is released through the reserved holes. The pressure escapes from the reserved holes. The reserved holes serve as pressure relief channels to guide the pressure release inside the battery. The pressure first breaks the folded position of the membrane layer. The triangular folded position of the membrane layer can buffer the pressure released by the battery, avoiding the danger caused by the impact force of the battery pressure release being too large. The adhesive acts as a secondary buffer for the battery, suppressing the speed and intensity of the pressure release, thereby improving battery safety.

[0025] 3. The reserved holes can limit the direction of battery pressure release, preventing the pressure inside the battery from being released over a large area and quickly igniting the battery pack. The design of the reserved holes can slow down the temperature diffusion and fire rate of the battery pack, further improving the safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a front view of the overall structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 3 This is a schematic diagram of the overall structure of the present invention (without folding corners);

[0029] Figure 4 It is a partial side view of the aluminum-plastic film structure of the present invention;

[0030] Figure 5 It is a partial side view of the aluminum-plastic film structure of the present invention.

[0031] In the figure: film layer (1), tab (2), edge sealing portion (3), folding line (4), reserved hole (5), stamping portion (6), and adhesive (7). DETAILED DESCRIPTION

[0032] The following is a combination of the embodiments of the present invention Figure 1-Figure 5 , the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0033] Example 1: Secondary battery aluminum-plastic film, including

[0034] The film layer 1 is provided with an edge sealing portion 3 and a liquid injection portion on the outside of the film layer 1, and a reserved hole 5 is opened on the surface of the film layer 1 and on the side away from the liquid injection portion. A folding line 4 is provided on the surface of the film layer 1 near the reserved hole 5, and the film layer 1 is folded along the folding line 4 to cover the reserved hole 5;

[0035] The membrane layer 1 is in the initial state as a sheet of membrane. First, a hole is punched on the surface of the membrane layer 1 and a reserved hole 5 is punched. The reserved hole 5 is close to the center line of the surface of the membrane layer 1 (such as Figure 2As shown), the film layer 1 is then folded along the center line and three sides are sealed to form the film layer 1 into a bag shape;

[0036] Furthermore, the folding line 4 is located at the corner of the film layer 1, and the corner of the film layer 1 is folded into a triangle along the folding line 4, so that the folding position is blocked by the reserved hole 5, and the triangular folding position of the film layer 1 is fixed to the surface of the film layer 1 by bonding or stamping or a combination of the two (such as Figure 5 As shown), at this time the reserved hole 5 is completely closed;

[0037] In order to improve the sealing performance of the reserved hole 5 and avoid leakage in the later stage, a glue 7 is glued outside the triangular folding position of the film layer 1 to improve the connectivity between the folding position and the film layer 1. The glue 7 is preferably made of the same material as the film layer 1. The folding position of the film layer 1 is protected by the glue 7 (such as Figure 3 as shown), to prevent wear and tear at this location.

[0038] Example 2: A bare core is placed inside a film layer 1, and a tab 2 is provided on one side of the bare core. The tab 2 corresponds to the liquid injection portion of the film layer 1. The electrolyte is injected into the bag structure from the liquid injection portion. After the liquid is injected, the liquid injection portion is sealed. The outer end of the tab 2 extends out of the film layer 1 and can be used to connect the current. At this time, the film layer 1 and the bare core form a soft-pack battery.

[0039] The film layer 1 is a three-layer composite material consisting of a nylon layer, an aluminum foil layer, and a heat-sealing layer. The soft-pack battery is encapsulated with an aluminum-plastic film. The aluminum-plastic film has high barrier properties, formability, electrolyte resistance, high temperature resistance, and puncture resistance. It has a good containment effect on the bare core and can ensure the quality of the soft-pack battery.

[0040] The reserved hole 5 is connected to the inside of the film layer 1. When the battery swells or explodes due to impact or damage, the internal pressure of the battery is released through the reserved hole 5. The pressure is released from the reserved hole 5. The reserved hole 5 serves as a pressure relief channel to guide the pressure inside the battery to be released. The pressure first breaks the folded position of the film layer 1. The triangular folded position of the film layer 1 can buffer the pressure released by the battery, avoiding the danger caused by the impact force of the battery pressure release being too large. The adhesive 7 also acts as a secondary buffer for the battery, suppressing the speed and intensity of the pressure release, thereby improving the safety of the battery.

[0041] The reserved hole 5 serves as a pressure relief channel to guide the pressure release inside the battery, which can limit the direction of the battery pressure release and avoid large-scale release of pressure inside the battery that quickly ignites the battery pack. The design of the reserved hole 5 can slow down the temperature diffusion of the battery pack and the speed of fire, further improving the safety of the battery.

[0042] In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless they contradict each other. The above is only an embodiment of the embodiment of this specification and is not intended to limit the embodiment of this specification. For those skilled in the art, the embodiments of this specification may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of this specification shall be included within the scope defined by the claims of this specification.

Claims

1. Aluminum-plastic film for secondary batteries, characterized in that: include The membrane layer is provided with an edge sealing portion and a liquid injection portion on the outside of the membrane layer, and a reserved hole is opened on the side of the membrane layer surface away from the liquid injection portion, and a folding line is provided on the surface of the membrane layer near the reserved hole, and the membrane layer is folded along the folding line to cover the reserved hole; The film layer is folded along the center line and sealed to form a bag shape, the reserved hole is connected to the inside of the film layer bag, the folding line is located at the edge corner of the film layer, and the film layer is folded in a triangle along the folding line; The triangular folding position of the film layer is fixed to the surface of the film layer by bonding or stamping or a combination of the two, the reserved hole is sealed at the triangular folding position of the film layer, and the triangular folding position of the film layer is bonded with glue.

2. The secondary battery aluminum-plastic film according to claim 1, characterized in that: The film layer is a composite material of a nylon layer, an aluminum foil layer and a heat-sealing layer.

3. The secondary battery aluminum-plastic film according to claim 1, characterized in that: The bag structure of the film layer contains a bare roll core, and a pole ear is provided on one side of the bare roll core, which corresponds to the liquid injection part of the film layer. The electrolyte is injected into the bag structure from the liquid injection part, and the liquid injection part is sealed and closed to form a soft-pack battery.

4. The secondary battery aluminum-plastic film according to claim 3, characterized in that: The outer end of the tab extends out of the film layer.

Images